Known capacitors are obtained by subjecting an anode body composed of a tantalum sintered compact or a niobium sintered compact to electrolytic oxidation in an aqueous solution of phosphoric acid to chemically convert the surface layer of the sintered compact into a dielectric composed of metal oxide. Tungsten is known as one of valve action metals. When an anode body composed of a tungsten sintered compact is subjected to electrolytic oxidation under the same conditions as the conditions of electrolytic oxidation of an anode body composed of a tantalum sintered compact or a niobium sintered compact, a sufficiently dense dielectric layer with a suitable thickness can be not obtained, and there seem to be many defects that an electric current flows when voltage is applied. Accordingly, capacitors in which conventional anode bodies made of tungsten is applied have large leakage current.